Hamstring spasticity assessment: does the hip flexion angle impact outcomes?

Purpose: Hamstring spasticity is prevalent following neurological injury. The standardized assessment involves passive knee extension, in a position of 90 degrees hip flexion. This creates passive insufficiency of the muscle and lacks ecological validity for walking, whereby the hip typically flexes to a maximum of 40 degrees during swing phase, while the knee extends. This study compared assessment outcomes when completed in 40 degrees and 90 degrees hip flexion.Methods: The Modified Ashworth Scale and Modified Tardieu Scale, were performed on 35 adults with a neurological condition. Each participant was assessed by three assessors, resulting in 105 trials at 40 degrees and 90 degrees.Results: There was a significant increase in the proportion of trials rated as spastic using the Modified Ashworth Scale (p=.012, phi=.27), and Modified Tardieu Scale (p<.001, phi=.36), and the severity of spasticity using the Modified Ashworth Scale (p<.001, effect size (ES)=.50), and Modified Tardieu Scale (p<.001 ES=.47), at 90 degrees hip flexion. The angle of reaction occurred 32 degrees earlier at 90 degrees hip flexion (p<.001, ES = 1.61).Conclusions: Completing hamstring assessments in 40 degrees hip flexion may reduce the passive insufficiency and improve the ecological validity of assessment, for walking. This may assist in the selection of patients requiring intervention, when their goal relates to walking.

Automated summary

Assessing hamstring spasticity at 90 degrees hip flexion resulted in more trials being rated as spastic and with higher severity compared to assessments at 40 degrees hip flexion. The angle of reaction also occurred earlier at 90 degrees hip flexion.